The present invention generally relates to memory storage apparatus, and more particularly, the invention concerns an improved memory storage apparatus having a linear actuator for reciprocatably positioning a transducer relative to a disc or other media upon which information is recorded. The actuator is referred to as a linear actuator because it is adapted to move the transducer along a straight line relative to the media of the memory storage apparatus.
The present invention provides a linear actuator particularly useful in a magnetic memory storage apparatus of the type known in the art as a Winchester magnetic disc memory storage apparatus. The actuator is situated adjacent the peripheries of several vertically spaced discs and is designed to rapidly position the transducers to access recorded disc information. The transducers normally comprise floating read/write heads. Although the present invention shall be described in connection with the Winchester disc drive unit, it will be appreciated that the actuator will be useful in other types of electromagnetic memory storage apparatus and also can be directly applied in optical memory storage apparatus wherein an optical transducer or several optical transducers are incorporated in the actuator.
The need for a compact, high capacity magnetic disc memory storage apparatus has generated much interest in recent years in the Winchester type of disc drive device. Due to the increased track density made possible by recent developments, there has been an ongoing attempt to provide an actuator capable of extremely rapid access time and yet which is compact. Although some actuators have been generally satisfactory, the known prior actuator designs have not been able to meet most of the following objectives: occupying a relatively small radial dimension at the peripheries of the rotating discs (e.g., approximately twice as great as the intended total stroke of the actuator); providing a sufficiently high magnetic force constant to both rapidly accelerate and decelerate the carriage (achieve extremely rapid access times) and also hold the carriage steady against minor vibrations transmitted to the actuator through the base of the storage apparatus; maintaining any magnetic leakage in front of the actuator adjacent the peripheries of the discs to a level well below that which would erase or adversely affect the information magnetically recorded on the surfaces of the discs; and providing a carriage support and drive arrangement which eliminates concerns about resonant vibrations induced by the required rapid acceleration and deceleration of the carriage.